Endogenous Losses of Nitrogen and Protein Requirement for Maintenance of Sheep

FOUR fistulated and four intact West African dwarf Sheep, maintained on hay and concentrate supplements were used for a study of metabolic faecal nitrogen (MEN) endogenous urinary nitrogen (EUN). The composition of the faecal losses was examined. The values obtained enabled calculation of nitrogen requirement of the sheep for maintenance, as well as the value of the experimental rations in the nutrition of the sheep. Values of MFN obtained by two methods were 3.31 and 3.10 g/kg Dry matter (DM) intake. Endogenous urinary nitrogen value was 0.024 g/day per metabolic weight (Wkg0.75.) Analysis of the faeces of the sheep showed that 21.1% of faecal nitrogen (N) were present as microbial and endogenous nitrogen (MEN) and 17.3% was present as water-soluble nitrogen. The biological values (BV) of the rations ranged from 85.7% to 100.0% and the digestibility for maintenance, were 1.20 and 0.41 g/day/Wkg 0.75 during the feeding trials. Values obtained for endogenous N losses and N requirement for low maintenance were low compared with reported values and this may indicate adaptation of the dwarf sheep for survival under inadequate dietary protein supply.

Studies on goat nutrition Part I. Minimum protein requirement of goats for maintenance-endogenous urinary nitrogen and metabolic faecal nitrogen excretion studies

1. EUN and MFN excretions have been determined in goats on a N-low ration and also on a N-free ration. The values obtained were,EUN = 0·052 g./kg. live weight andMFN = 0·41 g./100 g. dry-matter feed intake.2. The values so determined with the two feeding regimens, for both the EUN and MFN agreed very closely.3. The minimum protein requirement of goats for maintenance, as calculated from the EUN value, is 0·65 lb./1000 lb. live weight.4. The formula for calculating the utilizable protein requirement for this species is found to be P = 0·89. W0.734, and is almost identical with the one given by Mitchell.5. The usefulness of the above formula in predicting the EUN of immature goats is discussed.

Studies on goat nutrition Part II. Digestible protein requirements for maintenance from balance studies

1. The crude protein requirement of goats for maintenance has been determined from balance studies. The requirement per kg., as found by three different methods of treatments of the balance data, is practically the same, viz. 2·63 g. crude protein.2. The digestible crude protein requirement also has been calculated, again by two different methods, and is estimated at 1·12 lb./1000 lb. body weight. This value is undoubtedly very much higher than the value (0·65 lb./1000 lb.) obtained previously from the endogenous urinary nitrogen determinations alone.3. The dry-matter requirement of goat per 100 lb. live weight has been determined. Calculated on the basis of live weight raised to the power 0·734, the requirement was found to be 2·6 lb./100 lb.

THE ENDOGENOUS URINARY AND METABOLIC FECAL NITROGEN EXCRETIONS OF NEWBORN DAIRY CALVES

Daily observations were made on the fecal and urinary nitrogen excretions of four calves fed nitrogen-free diets during the second and fifth weeks after birth. The endogenous urinary nitrogen excretion was equivalent to 65.3 mg. per kg. of body weight (W) per day or 186 mg. per kg. W0.72. The metabolic fecal nitrogen excretion averaged 44.0 mg. per kg. of body weight per day or 0.334 per cent of the dry matter intake.